Bluetit bird feeding hungry young nestling in a garden bird box, The Cotswolds, Oxfordshire, England, United Kingdom

Bluetit hungry young nestling bird cheeping in a garden bird box, The Cotswolds, Oxfordshire, England, United Kingdom

Bluetit bird feeding hungry young nestling in a garden bird box, The Cotswolds, Oxfordshire, England, United Kingdom

Bluetit hungry young nestling bird awaits feeding in a garden bird box, The Cotswolds, Oxfordshire, England, United Kingdom

Newly hatched blue tit chicks and adult in a nestbox

Newly hatched blue tit chicks and adult in a nestbox

Bird nest boxes in the Forest of Bowland, Lancashire, England, United Kingdom, Europe

Mountain brushtail possum (Trichosurus caninus) emerging from artificial nestbox, hand-reared sub-adult male approximately 12 months old, Hopkins Creek, New South Wales, Australia, Pacific

Bluetit bringing food to its chicks in a nest box, England, United Kingdom, Europe

Tree Swallow, Tachycineta bicolor

Bird nesting box on a wooden telephone pole

Bird nesting box on a wooden telephone pole

Kestrel (Falco tinnunculus) perched inside a nestbox, England